There's a reason major device updates tend to roll out in stages. Some of the earlier recipients of the OnePlus One's big July OTA were hit with a bug where the PIN unlock screen did not display properly. OnePlus hasn't wasted any time hopping on this issue, and they're now pushing out a hotfix to the limited people who received the first OTA already and those who have flashed manually.
This update is so small that the version number remains the same, XNPH30O. Below we've shared the files for people who already downloaded the July update, as well as the full OTA zip for people who haven't updated yet and want to do everything in one go.
Download cm-bacon-0428073396-to-4f280f505a-signed.zip (Hotfix):
File size: 8.12 MB
Download cm-bacon-d22b777afa-to-4f280f505a-signed.zip (Full OTA):
File size: 113.7MB
Install: To install the update, boot into recovery, then sideload using adb sideload - if you've ever updated a Nexus device before, then you'll feel right at home, as the steps are exactly the same. If you're using TWRP, it will ask if you want to re-root at the end.
Source: CyanogenMod bug report